Biological Control In TheField

Kris BramanUniversity of Georgia

Why Use Natural Enemies?

Pests?Control AlternativesWhy “go biological” ?

The pesticide “treadmill”Target pest resurgence Secondary pest outbreaksPesticide resistance

Fewer pesticides availableHuman health and environmental

concerns

Know the Enemy- What is a Pest?

What is a Pest, really? Some Pests are Bigger than Others!Key Pests

Integrated Pest Management

IPMUse of all available tactics to

maintain pests at acceptable levels including:

MechanicalBiologicalCulturalChemical Regulatory

Target Pest Resurgence

Secondary Pest Outbreaks

Pesticide Resistance

Registered Pesticides (1914-1999)

Key Factors in Successful Pest Management

Scouting Proper Diagnosis Deciding on Control Tactic Implementation Follow-up Assessment

Turfgrass Food Web

Chinch bugs

Spittle bugs Caterpillars

Grubs

Big-eyed bug Parasitoid

Wolf spider

Groundbeetles

Tiger beetle

Ecological Basis of Biological Control

Add density dependent mortality factor

increase biotic pressure

reduced carrying capacity

Types of Biological Control

Conservation

Protection of existing biological control agents may be accomplished by: Use of pesticides only when necessary Spot sprays rather than blanket coverage Choice of pesticide that is least toxic to

beneficials Avoid or be selective in applying broad

spectrum or persistent pesticides Planting a variety of flowering species to

provide nectar and pollen sources and sources of alternative prey for predators

Providing shelter and moisture sources

Azalea Lace Bug (Azalea Lace Bug (Stephanitis pyrioidesStephanitis pyrioides))

Azalea lace bug adult

Azalea lace bug eggs

Azalea lace bug nymphs

ALB feedingthrough stomates

Cell content evacuation in palisade parenchyma layer

Parasitic wasp that attacks and kills lace bug eggs

Parasitized lace bug egg next to leaf midrib. Wasp has chewed a circularhole in the lace bug eggand emerged

Mymarid wasp next toAn azalea leaf hair

Five emergence peaks per year at 3 sites in a 2-yr study

Azalea plant bug (Rhinocapsus vanduzeei)adult and nymph, a predator that feeds on lace bugs, thrips, other small insectsand pollen

Pest Resistant Plants

Azalea growth in responseTo azalea lace bug feeding

Whole plant gas exchange measurements revealed thatphotosynthesis, carbon useefficiency and growth were not affected by lace bug injury < 13%

Augmentation

Release of additional beneficials when existing populations are too low Inoculative release: small number

released into an area of low pest infestation and progeny are sufficient to maintain low pest levels

Inundative release: large numbers of natural enemies are released often several times during a season

Augmentation of Natural Enemies

Augmentative releases of natural enemies

Uses in the US:

Predaceous mites Increasing in use Improved rearing

still based on natural foodsImproved shipping and release systems

envelopes with substrate, to place in plants Phytoseid mite consuming a spider mite

Augmentative Releases

Mite predators

PHOTO: Max Verkooy

L.Hull

Monitoring for mites

Importation (Classical)

Used most often against pests that have been accidentally introduced to the area where they are currently a problem

Natural enemies from the pest’s native region are introduced into the new area

Classical- Importation

In 1990 estimated that 722 biocontrol agents previously introduced into the US had resulted in suppression of 63 insect and mite pests

Most complete successes with Homopteran pests

PHM Parasite Release Program

Media Covering Florida’s First Parasite Media Covering Florida’s First Parasite ReleaseRelease

Pink Hibiscus MealybugHost PlantsFruits

Papaya Sugar-apple Golden apple Pigeon pea Carambola Soursop Cherry Passion fruit Avocado Mango Plum Grape Citrus Breadfruit Guava Banana

Ornamental Hibiscus Croton Allamanda Anthurium Heliconia Lantana Seagrape Bougainvillea Oleander Ixora Ginger lily Schefflera Ficus

VegetableTomatoPumpkinOkraLettuceBeansCucumberPeppersDasheenCabbageSquash

PHM Populations Reduced by Parasitoids

St. Kitts = 91.6 % US Virgin Islands

St. Thomas = 91.2%

St. Croix = 97.1%

Puerto Rico = 92% Culebra = 96.5% Vieques = 97.8% Belize = 96.6%

CaliforniaMulberry = 96%Carob = 93%

Bahamas = 82% (1 year)

Florida = 98.7% Haiti = 97.2% Dominican Republic =

96.6%

Mole Crickets

Identification and biology of some important predators

The first step in effectively using biocontrol is to correctly identify common natural enemies and to know what pests they are active against

Generalists vs. specialists Knowledge of the life cycle is

important; many natural enemies attack only a particular stage of a pest (egg, larva)

Spiders

PREDACEOUS MITE

Predatory beetles

LADY BEETLES

Turfgrass Cultivar Influences on Fall Armyworm Parasitism

S. Kristine BramanDepartment of Entomology

University of Georgia

Tigers in the Turf

Kris BramanUniversity of Georgia

Predators in the “True Bug” group

Predatory flies

Green Lacewing

LACEWING CAMOUFLAGE

Mantids

Paper Wasps

Parasitic wasps and flies

Azalea lace bug egg parasite

SCALE WITH PARASITE EMERGENCE HOLES

TACHINID EGGS ON CATERPILLAR

FUNGAL PATHOGEN

SCALE PATHOGEN

Managing Naturally Occurring Parasites and Predators

Choose selective rather than broad-spectrum insecticides May be slower, but long term control

is better achieved by using methods that conserve natural enemies

Monitor for beneficial arthropods as you would for pest insects If ratio of pests to natural enemies is

low, then spraying can be delayed